Synthesis of isatin derivatives under metal free conditions using hypervalent iodine

Hypervalent iodine(III)/TEMPO-mediated C(sp3), C(sp2) C-H bond oxidation of different oxindole and indole derivatives to their corresponding isatin derivatives was successfully achieved with excellent yields at room temperature. This metal-free method provides a direct access to potential synthon isatin that could be applied in the total synthesis of several biologically active natural products.